1. Field of the Invention
The present invention relates to umbrellas and, more particularly, to umbrellas of the generally large size used outdoors in the patio and garden and commonly referred to as "garden umbrellas", "patio umbrellas" or "market umbrellas".
2. Background Art
The conventional umbrellas and, more particularly, the larger sized patio, garden and market umbrellas generally are made with a rib support system attached to a means for extending and retracting the ribs to respectively open and close the umbrella. The umbrella commonly has a pulley and cord system wherein the pulley wheel is mounted at the top of the umbrella pole with one end of the pulley cord attached to the umbrella ribholder for lifting the ribs during opening of the umbrella while the other end of the pulley cord is pulled downward by either direct hand manipulation, such as is disclosed by Emanuel Dubinsky, the same inventor as the inventor in the present patent application, in U.S. Pat. No. 4,567,907 issued on Feb. 4, 1986, or by a mechanical hand crank mounted near the lower middle portion of the umbrella pole.
Due to the large size and heavy weight of conventional patio, garden and market umbrellas, various operating mechanisms have been employed to reduce the force otherwise required to raise the runner notch to spread and open the canopy. One such operating mechanism is a spring member disclosed by M.S. Robertson in U.S. Pat. No. 4,807,655 issued on Feb. 28, 1989. One problem with umbrellas of the type employing springs for automatic or assisted opening of the umbrella canopy is that the use of springs causes a non-constant or jerky motion wherein the umbrella operator loses the constant control over the operating path of the runner notch as it moves the ribs to open the canopy to its fully open position. Also, the tension exerted by a spring is highly variable, such that the spring exerts a high tension at one end of the opening cycle and relatively lower tension at the other end of such cycle. Finally, the use of spring mechanisms, as well as other mechanisms, such as the motor driven winding mechanism disclosed by V. Militano, et al in U.S. Pat. No. 3,129,715 issued on Apr. 21, 1964, involve complex parts, resulting in higher costs and a higher maintenance factor.
Also, it is generally necessary to secure the umbrella in its fully open position. This is usually accomplished in the large market umbrella by means of a locking pin which is inserted into a hole set near the top of the umbrella pole, such that the runner sits on top of the locking pin which prevents the umbrella canopy from closing. It would be desirable to provide a means whereby the umbrella is automatically held in its fully open position as it is opened with its runner reaching its highest position near the top of the pole.